Pigment granules

ABSTRACT

Pigment granules having an average particle size from 50 to 5000 μm and a BET surface area ≦15 m 2 /g, including as essential constituents
         (A) from 60 to 90% by weight of at least one pigment and   (B) from 10 to 40% by weight of at least one nonionic surface-active additive based on polyethers,
 
are prepared and used for pigmenting macromolecular organic and inorganic materials.

The present invention relates to novel pigment granules having anaverage particle size from 50 to 5000 μm and a BET surface area ≦5 m²/g,including as essential constituents

-   -   (A) from 60 to 90% by weight of at least one pigment and    -   (B) from 10 to 40% by weight of at least one nonionic        surface-active additive based on polyethers.

The invention also relates to the production of these pigment granulesand to their use for pigmenting macromolecular organic and inorganicmaterials.

Liquid systems such as coatings, varnishes, emulsion paints and printinginks are customarily colored using pigment formulations which includewater, organic solvent or mixtures thereof. As well as anionic,cationic, nonionic or amphoteric dispersants, these pigment formulationsgenerally have to be additized with further assistants, such asdried-crust inhibitors, freeze resistance enhancers, thickeners andanti-skinners, for stabilization.

There is a need for novel pigment preparations which are comparable tothe liquid formulations with regard to color properties anddispersibility, but do not require the additions mentioned and areeasier to handle. However, simply drying the liquid formulations doesnot provide solid pigment preparations having comparable applicationproperties.

U.S. Pat. No. 4,056,402 and U.S. Pat. No. 4,127,422 describe drynondusting pigment compositions for waterborne finish systems. However,these pigment compositions, as well as nonionic dispersants, include asan essential constituent at least 10% by weight of water-solublecellulose ethers or of water-dispersible polyvinyl compounds and hencediffer from the pigment granules of the present invention.

EP-A-84 645 and EP-A-403 917 disclose highly concentrated, solid pigmentformulations for coloring aqueous, alcoholic and aqueous/alcoholiccoatings and printing inks that include up to 30% by weight of anadditive based on reaction products of at least bifunctional amines withpropylene oxide and ethylene oxide but are present in finely dividedform.

It is an object of the present invention to provide solid pigmentpreparations having altogether advantageous application properties, inparticular high color strength and particularly good stir-indispersibility in a wide variety of application media.

Pigment granules having an average particle size from 50 to 5000 μm anda BET surface area ≦15 m²/g, including as essential constituents

-   -   (A) from 60 to 90% by weight of at least one pigment and    -   (B) from 10 to 40% by weight of at least one nonionic        surface-active additive based on polyethers.

The present invention further provides a process for preparing thepigment granules, which comprises wet-comminuting the pigment (A) inaqueous suspension in the presence of some or all of additive (B) andthen spray granulating the suspension, if applicable after the rest ofadditive (B) has been added.

The present invention yet further provides a process for pigmentingmacromolecular organic and inorganic materials, which comprisesincorporating pigment granules into these materials by stirring orshaking.

The pigment granules of the present invention include as essentialconstituents a pigment (A) and a nonionic surface-active additive (B).They are free of thickeners, such as cellulose ethers, and film formers,such as polyvinyl acetates and alcohols.

The average particle size of the pigment granules according to thepresent invention is in the range from 50 to 5000 μm, and especially inthe range from 100 to 1000 μm.

The BET surface area of the pigment granules according to the presentinvention is ≦15 m²/g, and preferably ≦10 m²/g.

Component (A) in the pigment granules of the present invention may be anorganic pigment or an inorganic pigment. It will be appreciated that thepigment granules may also include mixtures of various organic or variousinorganic pigments or mixtures of organic and inorganic pigments.

The pigments are present in finely divided form. Accordingly thepigments typically have average particle sizes from 0.1 to 5 μm.

The organic pigments are typically organic chromatic, white and blackpigments (color pigments). Inorganic pigments can likewise be colorpigments and also luster pigments and the inorganic pigments typicallyused as fillers.

There now follow examples of suitable organic color pigments:

-   -   monoazo pigments: C.I. Pigment Brown 25;        -   C.I. Pigment Orange 5, 13, 36, 38, 64 and 67;        -   C.I. Pigment Red 1, 2, 3, 4, 5, 8, 9, 12, 17, 22, 23, 31,            48:1, 48:2, 48:3, 48:4, 49, 49:1, 51:1, 52:1, 52:2, 53,            53:1, 53:3, 57:1, 58:2, 58:4, 63, 112, 146, 148, 170, 175,            184, 185, 187, 191:1, 208, 210, 245, 247 and 251;        -   C.I. Pigment Yellow 1, 3, 62, 65, 73, 74, 97, 120, 151, 154,            168, 181, 183 and 191;        -   C.I. Pigment Violet 32;    -   disazo pigments: C.I. Pigment Orange 16, 34, 44 and 72;        -   C.I. Pigment Yellow 12, 13, 14, 16, 17, 81, 83, 106, 113,            126, 127, 155, 174, 176 and 188;    -   disazo condensation C.I. Pigment Yellow 93, 95 and 128;    -   pigments: C.I. Pigment Red 144, 166, 214, 220, 221, 242 and 262;        -   C.I. Pigment Brown 23 and 41;    -   anthanthrone pigments: C.I. Pigment Red 168;    -   anthraquinone pigments: C.I. Pigment Yellow 147, 177 and 199;        -   C.I. Pigment Violet 31;    -   anthrapyrimidine    -   pigments: C.I. Pigment Yellow 108;    -   quinacridone pigments: C.I. Pigment Orange 48 and 49;        -   C.I. Pigment Red 122, 202, 206 and 209;        -   C.I. Pigment Violet 19;    -   quinophthalone pigments: C.I. Pigment Yellow 138;    -   diketopyrrolopyrrole    -   pigments: C.I. Pigment Orange 71, 73 and 81;        -   C.I. Pigment Red 254, 255, 264, 270 and 272;    -   dioxazine pigments: C.I. Pigment Violet 23 and 37;        -   C.I. Pigment Blue 80;    -   flavanthrone pigments: C.I. Pigment Yellow 24;    -   indanthrone pigments: C.I. Pigment Blue 60 and 64;    -   isoindoline pigments: C.I. Pigments Orange 61 and 69;        -   C.I. Pigment Red 260;        -   C.I. Pigment Yellow 139 and 185;    -   isoindolinone pigments: C.I. Pigment Yellow 109, 110 and 173;    -   isoviolanthrone pigments: C.I. Pigment Violet 31;    -   metal complex pigments: C.I. Pigment Red 257;        -   C.I. Pigment Yellow 117, 129, 150, 153 and 177;        -   C.I. Pigment Green 8;    -   perinone pigments: C.I. Pigment Orange 43;        -   C.I. Pigment Red 194;    -   perylene pigments: C.I. Pigment Black 31 and 32;        -   C.I. Pigment Red 123, 149, 178, 179, 190 and 224;        -   C.I. Pigment Violet 29;    -   phthalocyanine pigments: C.I. Pigment Blue 15, 15:1, 15:2, 15:3,        15:4, 15:6 and 16;        -   C.I. Pigment Green 7 and 36;    -   pyranthrone pigments: C.I. Pigment Orange 51;        -   C.I. Pigment Red 216;    -   pyrazoloquinazolone    -   pigments: C.I. Pigment Orange 67;        -   C.I. Pigment Red 251;    -   thioindigo pigments: C.I. Pigment Red 88 and 181;        -   C.I. Pigment Violet 38;    -   triarylcarbonium    -   pigments: C.I. Pigment Blue 1, 61 and 62;        -   C.I. Pigment Green 1;        -   C.I. Pigment Red 81, 81:1 and 169;        -   C.I. Pigment Violet 1, 2, 3 and 27;    -   C.I. Pigment Black 1 (aniline black);    -   C.I. Pigment Yellow 101 (aldazine yellow);    -   C.I. Pigment Brown 22.

Examples of suitable inorganic color pigments are:

-   -   white pigments: titanium dioxide (C.I. Pigment White 6), zinc        white, pigment grade zinc oxide; zinc sulfide, lithopone;    -   black pigments: iron oxide black (C.I. Pigment Black 11), iron        manganese black, spinel black (C.I. Pigment Black 27); carbon        black (C.I. Pigment Black 7);    -   chromatic pigments: chromium oxide, chromium oxide hydrate        green; chrome green (C.I. Pigment Green 48); cobalt green (C.I.        Pigment Green 50); ultramarine green;        -   cobalt blue (C.I. Pigment Blue 28 and 36; C.I. Pigment Blue            72); ultramarine blue; manganese blue;        -   ultramarine violet; cobalt violet;        -   manganese violet;        -   red iron oxide (C.I. Pigment Red 101); cadmium sulfoselenide            (C.I. Pigment Red 108); cerium sulfide (C.I. Pigment Red            265); molybdate red (C.I. Pigment Red 104); ultramarine red;        -   brown iron oxide (C.I. Pigment Brown 6 and 7), mixed brown,            spinel phases and corundum phases (C.I. Pigment Brown 29,            31, 33, 34, 35, 37, 39 and 40), chromium titanium yellow            (C.I. Pigment Brown 24), chrome orange;        -   cerium sulfide (C.I. Pigment Orange 75); yellow iron oxide            (C.I. Pigment Yellow 42); nickel titanium yellow (C.I.        -   Pigment Yellow 53; C.I. Pigment Yellow 157, 158, 159, 160,            161, 162, 163, 164 and 189); chromium titanium yellow;        -   spinel phases (C.I. Pigment Yellow 119);        -   cadmium sulfide and cadmium zinc sulfide (C.I. Pigment            Yellow 37 and 35); chrome yellow (C.I. Pigment Yellow 34);            bismuth vanadate (C.I. Pigment Yellow 184).

Examples of inorganic pigments typically used as fillers are transparentsilicon dioxide, ground quartz, aluminum oxide, aluminum hydroxide, zincsulfide, natural micas, natural and precipitated chalk and bariumsulfate.

Luster pigments are platelet-shaped pigments having a monophasic orpolyphasic construction whose color play is marked by the interplay ofinterference, reflection and absorption phenomena. Examples are aluminumplatelets and aluminum, iron oxide and mica platelets bearing one ormore coats, especially of metal oxides.

Component (B) in the pigment granules of the present invention is atleast one nonionic surface-active additive based on polyethers.

As well as unmixed polyalkylene oxides, especially polyethylene oxidesand polypropylene oxides, it is especially alkylene oxide blockcopolymers which are useful as component (B).

Copolymers comprising polypropylene oxide and polyethylene oxide blocksare very particularly suitable. They, like the unmixed polyalkyleneoxides, can be obtained by polyaddition of these alkylene oxides tosaturated or unsaturated aliphatic and aromatic alcohols and aliphaticamines, in which case these starter compounds are reacted with ethyleneoxide first and then with propylene oxide or preferably with propyleneoxide first and then with ethylene oxide.

Suitable aliphatic alcohols generally contain from 6 to 26 carbon atoms,preferably from 8 to 18 carbon atoms. Examples are octanol, nonanol,decanol, isodecanol, undecanol, dodecanol, 2-butyloctanol, tridecanol,isotridecanol, tetradecanol, pentadecanol, hexadecanol, 2-hexyldecanol,heptadecanol, octadecanol, 2-heptylundecanol, 2-octyldecanol,2-nonyltridecanol, 2-decyltetradecanol, oleyl alcohol and 9-octadecenoland also mixtures of these alcohols such as C₁₃/C₁₅ and C₁₆/C₁₈alcohols. Of particular interest are the fatty alcohols obtained fromnatural raw materials by fat hydrolysis and reduction and the syntheticfatty alcohols from the oxo process. The alkylene oxide adducts withthese alcohols typically have average molecular weights M_(n) from 400to 2000.

Useful aromatic alcohols, besides α- and β-naphthol and C₁–C₄-alkylderivatives thereof, include in particular phenol and its C₁–C₁₂-alkylderivatives, such as hexylphenol, heptylphenol, octylphenol,nonylphenol, isononylphenol, undecylphenol, dodecylphenol, di- andtributylphenol and dinonylphenol.

Useful aliphatic amines correspond to the above-recited aliphaticalcohols.

As well as the alkylene oxide adducts with these monofunctional aminesand alcohols it is the alkylene oxide adducts with at least bifunctionalamines and alcohols which are of very particular interest.

The at least bifunctional amines preferably have from two to five aminegroups and conform in particular to the formula H₂N—(R—NR¹)_(n)—H (R:C₂–C₆-alkylene; R¹: hydrogen or C₁-C₆-alkyl; n: 1–5). Specific examplesare: ethylenediamine, diethylenetriamine, triethylenetetramine,tetraethylenepentamine, 1,3-propylenediamine, dipropylenetriamine,3-amino-1-ethyleneaminopropane, hexamethylenediamine,dihexamethylenetriamine, 1,6-bis(3-aminopropylamino)hexane andN-methyldipropylenetriamine, of which hexamethylenediamine anddiethylenetriamine are more preferable and ethylenediamine is mostpreferable.

These amines are preferably reacted first with propylene oxide and thenwith ethylene oxide. The ethylene oxide content of the block copolymersis typically about 10–90% by weight.

The block copolymers based on polyamines generally have averagemolecular weights M_(n) from 1000 to 40000 and preferably from 1500 to30000.

The at least bifunctional alcohols preferably have from two to fivehydroxyl groups. Examples are C₂–C₆-alkylene glycols and thecorresponding di- and polyalkylene glycols, such as ethylene glycol,1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol,1,4-butylene glycol, 1,6-hexylene glycol, dipropylene glycol andpolyethylene glycol, glycerol and pentaerythritol, of which ethyleneglycol and polyethylene glycol are more preferable and propylene glycoland dipropylene glycol are most preferable.

Particularly preferred alkylene oxide adducts with at least bifunctionalalcohols have a central polypropylene oxide block, ie are based on apropylene glycol or polypropylene glycol which is initially reacted withfurther propylene oxide and then with ethylene oxide. The ethylene oxidecontent of the block copolymers is typically in the range from 10 to 90%by weight.

The block copolymers based on polyhydric alcohols generally have averagemolecular weights M_(n) from 1000 to 20000 and preferably from 1000 to15000.

Such alkylene oxide block copolymers are known and commerciallyavailable, for example under the names Tetronic® and Pluronic® (BASF).

Alkylene oxide block copolymers (B) are selected with differenthydrophilic-lipophilic balance (HLB) values, depending on theapplication medium in which the pigment granules of the presentinvention are to be used.

For use in aqueous, aqueous/alcoholic and alcoholic systems, preferenceis given to alkylene oxide block copolymers (B) having HLB values ofabout a ≧10, which corresponds to an ethylene oxide content of thecopolymers of generally ≧25% by weight.

For use of the pigment granules of the present invention inhydrocarbonaceous, eg mineral oil containing or xylenic systems orsystems based on nitrocellulose, alkylene oxide block copolymers (B)having HLB values of about <10 are particularly suitable, this HLB valuecorresponding to an ethylene oxide content of the copolymers ofgenerally <25% by weight.

The pigment granules of the present invention include from 60 to 90% byweight and preferably from 70 to 85% by weight of component (A) and from10 to 40% by weight and preferably from 10 to 30% by weight of component(B).

They are advantageously obtainable by the process of the invention bywet-comminuting the pigment (A) in aqueous suspension in the presence ofsome or all of the nonionic additive (B) and then spray granulating thesuspension, if applicable after the rest of additive (B) has been added.

Pigment (A) can be used in the process of the present invention as a drypowder or in the form of a presscake.

Pigment (A) as used is a finished product, ie the primary particle sizeof the pigment has already been adjusted to the desired applicationvalue. This finish is necessary in the case of organic pigmentsespecially, since the as-synthesized crude material is not suitable foruse. In the case of inorganic pigments, for example in the case of oxideand bismuth vanadate pigments, the primary particle size may also beadjusted in the course of the synthesis of the pigment, so that theas-synthesized pigment suspensions can be used direct in the process ofthe present invention.

Since the finished pigment (A) typically reagglomerates in the course ofdrying or on the filter assembly, it is subjected to wet comminution,for example grinding in a stirred media mill, in aqueous suspension.

The wet comminution should be carried out in the presence of at least aportion of the additive (B) for the ready-produced pigment granules, andit is preferable to add the entire amount of additive (B) prior to thewet comminution.

Spray granulation is preferably carried out in a spray tower using aone-material nozzle. Here, the suspension is sprayed in the form ofrelatively large drops, and the water evaporates. Additive (B) melts atthe drying temperatures and so leads to the formation of a substantiallyspherical granule having a particularly smooth surface.

The gas inlet temperature in the spray tower is generally in the rangefrom 180 to 300° C. and preferably in the range from 150 to 300° C. Thegas outlet temperature is generally in the range from 70 to 150° C. andpreferably in the range from 70 to 130° C.

The residual moisture content of the granular pigment obtained isgenerally <2% by weight.

The pigment granules of the present invention are notable in use fortheir excellent color properties which are comparable to those of liquidpigment formulations, especially with regard to color strength,brilliance, hue and hiding power, and especially for their stir-incharacteristics, ie they can be dispersed in application media with aminimal input of energy, simply by stirring or shaking.

Compared with liquid pigment formulations, the pigment granules of thepresent invention additionally have the following advantages: They havea higher pigment content. Whereas liquid formulations tend to changeviscosity in the course of storage, and have to be admixed withpreservatives and agents for enhancing the resistance to freezing and/ordrying out, the pigment granules of the present invention exhibit verygood stability in storage. They are both economically and ecologicallyadvantageous with regard to packaging, storage and transportation. Sincethey are solvent free, they are more flexible in use.

The pigment granules of the present invention are notable for excellentattrition resistance, a minimal tendency to compact or clump, uniformparticle size distribution, good pourability, flowability andmeterability, and also dustlessness in handling and application.

The pigment granules of the present invention are very useful forpigmenting macromolecular organic and inorganic materials of any kind.Liquid application media in this context can be purely aqueous, comprisemixtures of water and organic solvents, for example alcohols, or bebased exclusively on organic solvents, such as alcohols, glycol ethers,ketones, eg methyl ethyl ketone, amides, eg N-methylpyrrolidone anddimethylformamide, esters, eg ethyl acetate, butyl acetate andmethoxypropyl acetate, or aromatic or aliphatic hydrocarbons, eg xylene,mineral oil and mineral spirits.

When the HLB value of the additive (B) included in the pigment granulesof the present invention has not been adapted to the character of theapplication medium, as described above, the granules can initially bestirred into a solvent which is compatible with the particularapplication medium, and this stirring into the solvent is again possiblewith minimal input of energy, and then be introduced into thisapplication medium. For instance, slurries of pigment granules havinghigh HLB values in glycols or other solvents customary in the paint andcoatings industry, such as methoxypropyl acetate, can be used to renderthe pigment granules compatible with hydrocarbonaceous systems orsystems based on nitrocellulose.

Examples of materials which can be pigmented with the pigment granulesof the present invention include: coatings, for example architecturalcoatings, industrial coatings, automotive coatings, radiation-curablecoatings; paints, including paints for building exteriors and buildinginteriors, for example wood paints, lime washes, distempers, emulsionpaints; solventborne printing inks, for example offset printing inks,flexographic printing inks, toluene intaglio printing inks, textileprinting inks, radiation-curable printing inks; waterborne inks,including inkjet inks; color filters; building materials (water istypically added only after building material and granular pigment havebeen dry mixed), for example silicate render systems, cement, concrete,mortar, gypsum; bitumen, caulks; cellulosic materials, for examplepaper, paperboard, cardboard, wood and woodbase, which can each becoated or otherwise finished; adhesives; film-forming polymericprotective colloids as used for example in the pharmaceutical industry;cosmetic articles; detergents.

EXAMPLES

Production and Testing of Pigment Granules According to Invention

The pigment granules were produced by ball milling a suspension of 20 kg(Example 1: 35 kg) of additive (B) and 80 kg of finished pigment (A) toa d₅₀ value of 0.8 μm, and then spray granulating the mixture in a spraytower using a one-material nozzle (gas inlet temperature 170° C., gasoutlet temperature 80° C.).

The color strength of the pigment granules was determinedcolorimetrically in the white reduction (reported in terms of the DIN55986 coloring equivalents (CE)) in a waterborne emulsion paint. To thisend, a mixture of in each case 1.25 g of granular pigment and 50 g of awaterborne styrene-acrylate-based test binder having a white pigmentcontent of 16.4% by weight (TiO₂, Kronos 2043) (BASF test binder00-1067) was homogenized in a 150 ml plastic beaker by running a highspeed stirrer at 1500 rpm for 3 min. The color obtained was then drawndown on a black and white test card using a 100 μm wire-wound filmapplicator and dried for 30 min.

The corresponding emulsion paints produced using commercially availableaqueous formulations of the pigments were assigned the CE value of 100standard. CE values <100 mean a higher color strength than that of thestandard, CE values >100 accordingly a lower color strength.

The table hereinbelow lists details of the pigment granules produced(composition, d₅₀ median average particle size, BET surface area) andalso the respectively obtained CE values. The nonionic additives (B)used were as follows:

-   -   B1: block copolymer based on ethylenediamine/propylene        oxide/ethylene oxide, having an ethylene oxide content of 40% by        weight and an average molecular weight M_(n) of 12000    -   B2: block copolymer based on ethylenediamine/propylene        oxide/ethylene oxide, having an ethylene oxide content of 40% by        weight and an average molecular weight M_(n) of 6700    -   B3: propylene oxide/ethylene oxide block copolymer having a        central polypropylene oxide block, an ethylene oxide content of        50% by weight and an average molecular weight M_(n) of 6500

TABLE Ex. Pigment (A) Additive (B) d₅₀ [μm] BET [m²/g] CE 1 C.I. P. Y.42 B1 330 4 110 2 C.I. P. Y. 74 B3 270 2 108 3 C.I. P. Y. 138 B3 280 1105 4 C.I. P. Y. 184 B1 300 1 105 5 C.I. P. R. 101 B1 320 4 107 6 C.I.P. R. 112 B1 330 1 106 7 C.I. P. R. 122 B1 280 2 106 8 C.I. P. V. 19 B1270 1 108 9 C.I. P. V. 23 B1 290 1 108 10 C.I. P. B. 15:2 B2 300 3 10911 C.I. P. B. 15:3 B1 300 8 105 12 C.I. P. G. 7 B1 280 1 107 13 C.I. P.Bk. 7 B1 310 5 108

1. Pigment granules having an average particle size from 50 to 5000 μmand a BET surface area ≦15 m²/g, consisting of (A) from 60 to 90% byweight of at least one pigment and (B) from 10 to 40% by weight of atleast one nonionic surface-active additive based on polyethers, whereinsaid component (B) comprises ethylene oxide- or propylene oxide- ormixed ethylene oxide/propylene oxide-adducts with amines or alcohols, orethylene oxide/propylene oxide block copolymers, obtained bywet-comminution of said pigment (A) in aqueous suspension in thepresence of some or all of said additive (B) and subsequent spraygranulation of said suspension, if applicable after the rest of additive(B) has been added.
 2. Pigment granules as claimed in claim 1, whereinsaid component (B) comprises block copolymers obtained by sequentialpolyaddition of propylene oxide and ethylene oxide to at leastbifunctional amines or alcohols.
 3. A process for producing pigmentgranules as claimed in claim 1, which comprises wet-comminuting saidpigment (A) in aqueous suspension in the presence of some or all of saidadditive (B) and then spray granulating said suspension, if applicableafter the rest of said additive (B) has been added.
 4. A process asclaimed in claim 3, wherein said spray granulating is effected in aspray tower using a one-material nozzle.
 5. A process for pigmentingmacromolecular organic or inorganic materials, which comprisesincorporating pigment granules as claimed in claim 1 into thesematerials by stirring or shaking.
 6. A process as claimed in claim 5,wherein said macromolecular organic or inorganic materials arepigmenting coatings, paints, inks, building materials or cellulosicsystems, where a liquid phase comprises water, organic solvents ormixtures of water and organic solvents.
 7. Pigment granules as claimedin claim 1, wherein the average particle size is from 100 to 1,000 μmand the BET surface area is ≦10 m²/ g.
 8. Pigment granules as claimed inclaim 1, wherein component (B) is at least one selected from the groupconsisting of ethylenediamine/polypropylene oxide/ethylene oxide blockcopolymers, ethylene oxide/polypropylene oxide/ethylene oxide blockcopolymers, and ethylene oxide adducts with fatty alcohols.
 9. Pigmentgranules as claimed in claim 8, wherein component (B) comprises anethylenediamine/polypropylene oxide/ethylene oxide block copolymer. 10.Pigment granules as claimed in claim 8, wherein component (B) comprisesan ethylene oxide/polypropylene oxide/ethylene oxide block copolymer.11. Pigment granules as claimed in claim 8, wherein component (B)comprises an ethylene oxide adduct with a fatty alcohol.